The present invention relates to a fluid plant which comprises a plurality of system apparatus.
In a nuclear power plant containing a fluid such as cooling water, for example, in a normal-use equipment of a conventional boiling water reactor, three systems of condensate system pumps each having a 50% capacity are provided in parallel, as shown in FIGS. 5 and 6, and one of the systems is used as a stand-by system (a spare system). As feed water system pumps, two systems of turbine driven pumps each having a 50% capacity are provided for normal use, and one system of a motor driven pump having a 25% capacity is provided as a stand-by system (a spare system). In the equipment provided with such stand-by system apparatus, when an abnormality occurs in apparatus of one of the systems during normal operation, this system where the abnormality has occurred is firstly stopped, and the systems are switched to start the apparatus of the stand-by system. Thereafter, maintenance inspection of the apparatus in the system where the abnormality has occurred is performed, and also, operation of the plant is continued with the apparatus in the stand-by system and the apparatus of the other normally functioning system, thus preventing operational efficiency and reliability of the equipment from deteriorating.
In a reactor water clean-up system, however, two systems of pumps each having a 50% capacity are only provided for normal use, and no spare pump is provided. Therefore, in the equipment without stand-by system apparatus, when an abnormality occurs in apparatus of one of the systems during operation, the entire plant must be stopped to perform maintenance of the apparatus in question.
In the above-described equipment provided with the stand-by system apparatus, it is necessary to start the stand-by system apparatus quickly at the time of occurrence of an abnormality. Generally, the stand-by system apparatus are in a stopped condition until they receive a start signal produced a result of occurrence of an abnormality. In response to the start signal, power is supplied from an emergency power supply, and operation of the stand-by system apparatus is started. However, a start-up failure probability of a diesel-engine generator serving as the emergency power supply is relatively higher than that of other apparatus, and consequently, it is probable that power supply to the stand-by system apparatus will fail, and that the standby system apparatus can not be started. When starting of the stand-by system apparatus fails, conditions of normal operation can not be quickly recovered in substantially the same manner as the equipment without stand-by system apparatus, thereby deteriorating operational efficiency (availability) of the equipment. Also, maintenance of the apparatus during normal operation can not be conducted, and maintenance efficiency can not be improved.